Use getTitle() for AccessPoint display name

Instead of getSsidStr(), AccessPoint display names should use
getTitle() to accomodate Passpoint networks which use a provider
name instead of a single ssid. This change allows the provider
name to be displayed in the network details page, the long
press wifi dialog, and the config editing dialog.

Bug: 118705403
Test: atest WifiSettingsTest
Change-Id: I930d6218c7e464ad20c0c61130e0cb9ce315d9a2